Ryan Braun is about to learn just how precious a good name is. When one is lost, it's usually lost forever. He now faces the monumental challenge of trying to get his back.

Here's hoping he understands that he only gets one chance. When he discusses the matter publicly on Friday, he should tell the entire story, from beginning to end, warts and all. He only has to do it once, but he has to understand there aren't any do-overs.

If he trots out one version on Friday and then tries another three days later and still another five days after that, he's finished. He's fighting for something way more important than a 50-game suspension. He also appears to be fighting an uphill battle.

If reports that his suspension was overturned because his urine sample wasn't shipped to the testing lab in a timely matter are accurate, he has got a tough sell on his hands.

If that's the case, he should remember how Andy Pettitte dealt with the Mitchell Report's revelation that he used human growth hormone (HGH). Pettitte called a news conference and said he'd made a terrible mistake and that he hoped people would forgive him.

Then he went out and resumed his career, pitching three more years, with HGH becoming nothing more than a tiny footnote of a long and distinguished resume.

Braun once had one of baseball's best reputations. He was a guy who did everything right, from being one of the game's best players on the field to one of its role models off of it.

All that disappeared in December when it was revealed he'd tested positive for a banned substance. Braun declared his innocence but was vague about it, declining to offer specifics.

Even those of us who wanted to believe him were skeptical, because his denial sounded like every other in recent years. Yet he'd been tested throughout his professional career and had seen enough reputations ruined to know the damage that could be done. It seemed improbable that he decided the reward outweighed the risk.

Besides that, his body hadn't changed significantly. His productivity didn't vary much, either. In five seasons he hit 34, 37, 32, 25 and 33 home runs. His consistency has been part of what made him special.

Despite all the evidence that Braun wasn't like most of the others who were caught, his positive test spoke volumes. Baseball's drug-prevention program is handled by the Olympics testing lab, arguably the best on earth.

Baseball's drug-testing policy is based on a simple premise: Every player is responsible for what he puts in his body, no exceptions allowed.

No medication, no supplement, no vitamin is to be taken without the approval of a team's medical staff. Players are routinely warned to be cautious about taking anything that hasn't been approved.

When Braun's positive test was revealed, there didn't seem to be any hope of having the 50-game suspension overturned, but Braun did succeed in convincing arbitrator Shyam Das that his should be. Major League Baseball, perhaps foreseeing a flood of appeals -- including appeals for positive tests from years past -- sharply criticized the decision.

If you're thinking that Braun's successful appeal calls the entire program into question, take a deep breath. This is the 10th spring that players have been tested for steroids, and by almost any measuring stick, the program has been wildly successful.

We're likely to learn more about Braun's test over the next few weeks, and here's betting that no significant flaw will be found in the program.

For now, Braun's challenge will be explaining what he did and why, to be completely forthcoming and to begin the process of rehabilitating his image. This part of the deal is tougher than winning the appeal in the first place.

Some people will never believe he's clean. That's true of some players, too. Braun shouldn't worry about those people. All he should concern himself with is the truth. Lay it out for all to see, then go back to being what he has always been -- one of baseball's best players and most popular stars.

In time, this whole thing may be only a minor part of Braun's story. But it'll take time. It'll also take him being unafraid of the truth. He only has one chance.

Richard Justice is a columnist for MLB.com. Read his blog, Justice4U. This story was not subject to the approval of Major League Baseball or its clubs.